The present invention relates to guide wires, catheters and elongate devices used in the vessels, ducts, and lumens of a living being, and more particularly to a system for facilitating the delivery and exchange of such catheters, devices, and guide wires to various locations within the body of a living being.
As will be appreciated by those skilled in the art, various medical procedures involve the use of catheters and guide wires that are inserted into various locations within a living being. By way of example, for the treatment of some vascular diseases, such as atherosclerosis, it is common practice to insert an instrument (e.g., catheter, guide wire, etc.) into a vessel to perform a procedure that reduces or eliminates a restriction or stenosis. Such procedures, known as percutaneous catheterization intervention (PCI), typically involve several steps. To begin, an initial puncture is created in a vessel that is typically remote from the stenosis. Next, a guide wire is inserted through the puncture and threaded into the vessel. A guiding catheter is then advanced in to the patient's arteries. A guide wire is then advanced through the guiding catheter and, for the treatment of coronary disease, into the patient's coronary arteries. The guide wire is maneuvered by advancing and rotating the distal tip, which normally has an asymmetric “J” shape imposed on it to enable the selection of various branches of the coronary vasculature. Once the wire is in the desired position, a diagnostic or therapeutic catheter, which has a lumen or other means adapted to receive the guide wire, is then guided along the wire to the desired location.
In the course of a typical PCI, for example, an angioplasty procedure, the catheter has a distally mounted balloon that can be placed, in a deflated condition, within the stenosis, and then inflated to dilate the narrowed lumen of the blood vessel. Such balloon dilation therapy is generally referred to as percutaneous transluminal angioplasty (PTA). Percutaneous transluminal coronary angioplasty (PTCA) is used when the treatment is more specifically employed in vessels of the heart. PTCA is used to open coronary arteries that have been occluded by a build-up of cholesterol fats or atherosclerotic plaque. The balloon at the distal end of the catheter is inflated, causing the site of the stenosis to widen. In some cases, a stent, a cylindrically shaped device formed from wire(s) or a metal tube, is placed at the site of the restriction to act as a prosthesis that provides support to the body lumen. In addition to angioplasty and stealing procedures, other diagnostic and therapeutic procedures require the use of wires and catheters, such as drug delivery, embolic protection, angiography, atherectomy, imaging and other treatments known in the art.
During these procedures, the guide wire plays an important role in guiding the diagnostic or therapeutic device (e.g., catheter) to the desired location in the patient's body. For example, one difficulty that can be encountered in the procedure is the inability to cross the lesion or stenosis with the distal end of the guide wire. This can be the result of a variety of situations, including a tight stenotic lesion with insufficient lumen patency to allow passage of a guide wire. In other instances, the vessel can be completely blocked as in the case of a chronic total occlusion (CTO). In cases such as these, the physician may need to utilize a different guide wire and thus replace an in-situ wire with another having different construction, structure or properties, e.g., floppy-tip design or shape, stiffness, etc. The need to withdraw an already placed guide wire also occurs when the distal tip of the guide wire needs to be reshaped to pass a blockage or navigate into the desired vessel. Because of this, there exists a need for the physician to be able to exchange guide wires while supporting a pre-positioned guide wire to facilitate crossing of a difficult lesion.
The manner in which the catheter integrates with the guide wire during the procedure can have significant impact on she timing, ease of use, and ultimate success of the procedure. In general, there are four types of wire-catheter systems:
1. Over-the-wire (OTW),
2. Multi-Exchange (MX),
3. Rapid Exchange (RE), and
4. Fixed Wire (FW).
OTW, MX and RE catheters require the use of a guide wire that is separate from the catheter while a FW catheter has an integral guide wire. An OTW catheter comprises a guide wire lumen that extends the entire length of the catheter. The guide wire is disposed entirely within the catheter guide wire lumen except for distal and proximal portions of the guide wire, which extend beyond the distal and proximal ends of the catheter respectively. An MX catheter is arranged such that it has an over-the-wire configuration while the catheter is within the patient's body, but the wire exits the side of the catheter through a zipper-like, longitudinal slit configuration at a location outside the body.
OTW and MX catheters provide a full length guide wire lumen, whereas RE catheters provide a short guide wire lumen only at or near the distal end. However, traditional OTW, MX and traditional RE catheters do suffer some shortcomings. For example, it often becomes necessary, in the performance of a PCI, to exchange one indwelling catheter for another catheter. In order to maintain a guide wire in position while withdrawing an OTW catheter, the guide wire must be gripped at its proximal end to prevent it from being pulled out of the blood vessel with the catheter. For example, a PTCA catheter, which may typically be on the order of 135 centimeters long, is longer than the proximal portion of the standard guide wire that protrudes out of patient. Therefore, exchanging an over-the-wire PTCA catheter requires an exchange guide wire of about 300 centimeters long, whereas a standard guide wire is about 165 centimeters long. Wires of this length can be difficult to control in the surgical field, and it is not uncommon for a portion of such a long wire to inadvertently touch the floor or other non-sterile location in the catheterization laboratory, thereby requiring removal of the wire from the patient and the reinitiating of the procedure with a new wire. Other techniques are known in the art for performing wire exchange with OTW catheter yet regardless of which exchange process is used, the very long exchange guide wire is awkward to handle, often requiring at least two operators to perform the procedure.
RE catheters were developed in an attempt to simplify the procedure for exchanging wires and catheters. Catheters of this type are formed so that the guide wire is located outside of the catheter except for a short guide wire lumen that extends within only a comparatively short distal segment of the catheter. The RE catheter's proximal exit port for the guide wire is typically located about 5 cm (2.0 in) to 30 cm (11.8 in) proximal to the catheter's distal end. In use, the guide wire is placed initially in the patient's vascular system. The distal segment of the RE catheter then is threaded onto the wire. The catheter can be advanced alongside the guide wire with its distal segment sliding along the guide wire. The RE catheter can be removed and exchanged for another RE catheter without the use of a very long exchange guide wire and without requiring withdrawal of the initially placed guide wire.
However, one shortcoming associated with RE catheters is that it is not possible to exchange guide wires in an indwelling RE catheter, as can be done with OTW catheters. A guide wire can be withdrawn, sometimes accidentally, from the proximal guide wire port, thus derailing an indwelling RE catheter. However, neither the first guide wire, nor a replacement guide wire, can be directed back into the catheter's proximal guide wire port, which is located within the patient.
In addition to exchanging catheters over guide wires, it is also sometimes desirable to exchange one guide wire for another guide wire having a different feature. Over the years, specialty guide wires have been developed possessing different characteristics with respect to size, length, flexibility, tip shape, etc. to provide the physician with the proper wire for each unique medical circumstance. For example, when a physician encounters highly tortuous anatomy, a relatively soft and flexible guide wire is typically employed because they can be easily placed at the desired location and they have enough stiffness for guiding a flexible diagnostic angiography catheter through the vasculature. However, a shortcoming of these highly flexible wires is that their degree of flexibility makes them poor wires for guiding stiffer and larger therapeutic catheters (e.g., stent delivery catheters) through the same tortuous vasculature region. These stiffer catheters often require a guide wire that is relatively stiffer as well. In these instances it is desirable to place a second, more suitable, guide wire at the desired treatment site.
It is known in the art that dual lumen catheters can be used to exchange one wire for another. The first lumen of the catheter is used to guide the catheter along the initial wire and the second lumen is then used to deliver a second wire to the location of the first. A shortcoming of these systems is that the presence of dual lumens extending the length of the catheter makes them quite large (i.e., in effective diameter), limiting how far they may be advanced into the body, as well as affecting their flexibility. Furthermore, they require the use of double length wires, which is a tedious procedure with accompanying safety issues, as described previously.
Alternatively, it is known in the art to employ a rapid exchange delivery sheath, which utilizes only a short lumen segment for guiding an exchange catheter over the primary guide wire. This allows the primary wire to be of a shorter length, however the second wire must be double length to allow removal of the exchange catheter.
MX catheters include a longitudinal slit extending most of the length of the catheter, through which a wire may be removed laterally, or “peeled off”. At the distal end of the catheter is a short segment lacking the longitudinal slit, similar in nature to the short, segment of a RE catheter. In use, a guide wire may be inserted at the proximal end of the catheter, and advanced through the central lumen of the catheter, much like an OTW catheter. However to remove the MX catheter, and not remove the wire, the proximal end of the wire (outside of the body) is laterally removed through the slit provided in the catheter wall. While holding the wire in position, the catheter is retracted, and removed from the wire through the length of the longitudinal slit of the catheter, in effect, peeling the catheter away from the wire as the catheter is retracted. As the catheter is peeled off, and the catheter is retracted until the wire encounters the distal end of the slit, whereupon there remains a short segment of the catheter that may be removed in a manner similar to that for a RE catheter. The MX procedure offers the benefit of an internal lumen delivery of the wire, similar to an OTW, but allows the user to avoid a double length catheter, similar to a RE catheter. However, the required “peeling-off” procedure is tedious as it requires holding onto the proximal end of the wire, and careful removal is required, as great care must be taken to ensure that the peeling off procedure does not crimp or otherwise damage a wire, and also to ensure that there are no movements as the wire is pulled through the longitudinal slit that would dislodge the distal end of the wire from the target location or vessel. The “peeling off” procedure may be acceptable with robust, large diameter wires, however the procedure is ill suited for use with specialized, narrow diameter guidewires, as may be required to reach far into tortuous vasculature or effect a difficult crossing of a lesion, as these wires are more sensitive to damage, such as crimping or breaking, when the MX catheter is retracted and removed.
It is known in the art, for example, in U.S. Pat. Nos. 6,537,294 and 6,652,505, 6,142,987, and published US Application Nos. 2002/0095141 and 2004/0059372, that a catheter can be constructed where two short lumen segments are mounted on a mandrel or third wire. This device is used to deliver a filter device, housed in one short lumen, along a guide wire, housed in the second short lumen. A short-coming of this system is that there is no method for securing she filter in the short monorail segment other than the surface contact between the expandable filter and the internal surface of the short lumen of the monorail.
U.S. Pat. No. 4,947,864 describes a guide wire exchange catheter employing a MX procedure for peeling away the exchange catheter after the satisfactory placement of a second (replacement) guide wire. As the operator advances the exchange catheter into the patient, he also grasps a second (replacement) guide wire which has its distal end directed through the distal end portion of the exchange catheter. While grasping both the exchange catheter and the second guide wire at a location outside of the patient, the operator simultaneously advances both the exchange catheter and the replacement guide wire further into the patient, following along the first guide wire. The '864 patent does not provide for a way to secure the distal end of the second guide wire in place within the exchange catheter, therefore the operator must take great care to simultaneously grasp and advance the wire and catheter together. Once at the desired site, the wire may be left in place and the catheter must then be peeled off, taking care not to crimp the wire, nor dislodge it from the desired site.
U.S. Pat. No. 6,605,062 (Hurley et al.) describes a catheter for guide wire support or exchange having a longitudinal slit in the catheter to allow a guide wire exchange using a MX procedure where the catheter is peeled off of a second guide wire while the catheter is being retracted. Hurley et al. also provide for an axial support member secured to the elongate shaft to provide axial rigidity to the catheter. There is no provision for releasably locking or securing a guide wire in place within the exchange catheter.
What is needed is a reliable easy to use system to exchange one guide wire for another with out the need for double length guide wires. There is further a need where the delivery of the secondary guide wire, which is to be exchanged with the initial guide wire, is accomplished in a rapid, safe, and secure manner, where there is provided an exchange or shuttle catheter which is advanced over a primary wire, and where the exchange catheter securely carries or pulls along a second wire to the target site. Furthermore, there is a benefit to providing an elongate, flexible device that has a low, compact profile at the distal end to better navigate tortuous anatomy. Moreover, the system should be relatively easy to insert and remove from the patient's vasculature.